The present invention relates to a compressor. More particularly, the present invention relates to a structure of the compressor that improves sealing performance at facing surfaces of a housing and a cylinder block.
A piston type compressor such as a swash plate type compressor generally includes suction and discharge chambers defined in a housing such that a partition wall separates the suction and discharge chambers. A cylinder block facing the suction and discharge chambers is disposed in the housing so as to sandwich a valve plate assembly. Cylinder bores each slidably accommodate respective pistons. Refrigerant gas in the suction chamber is sucked into the cylinder block and the refrigerant gas in the cylinder block is discharged to the discharge chamber by reciprocation of the pistons. Due to the suction and discharge of the refrigerant gas, large pressure difference arises at the partition wall.
To improve sealing performance at the partition wall, Japanese Unexamined Patent Publication No. 11-303743 discloses a compressor that includes the convex end of a cylinder head facing the partition wall of the housing.
Sealing performance at the partition wall improves because pressure applied to the partition wall increases due to the convex end of the cylinder head. However, an unwanted effect is that sealing performance at the cylinder head adjacent to the outer periphery is deteriorated because pressure applied to the surface of the cylinder head adjacent to the outer periphery reduces.
Particularly, high sealing performance is required when refrigerant gas such as carbon dioxide is used in the compressor in a state of a relatively high pressure condition.
The present invention addresses the above-mentioned problems traceable to large pressure difference between a suction chamber and a discharge chamber by improving sealing performance at mutual facing surfaces between a housing and a cylinder block.
According to the present invention, a compressor has a housing and a cylinder block. The housing includes suction and discharge chambers. The cylinder block is fixed to the housing via a valve plate assembly. The valve plate assembly forms suction and discharge ports and suction and discharge valves. A partition wall is formed with the housing, and separates the suction chamber and the discharge chamber. The housing includes a first surface, and the cylinder block includes a second surface. At least one of the first and second surfaces is concave in shape. The cylinder block is screwed to the housing at the partition wall or a position closer to the central axis of the housing than the partition wall by a bolt so that the first surface faces the second surface.
Pressure is applied to the partition wall by screwing the cylinder block to the housing. Since at least one of the first and second surfaces is concave in shape, pressure is applied to the first and second surfaces adjacent to the outer periphery after screwing the cylinder block to the housing by the bolt.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.